Mobile stations operate in various operating modes, use different technologies, and utilize different protocols as they move across different networks or across the same network. For example, mobile stations may operate according to frequency division multiple access (FDMA) or time division multiple access (TDMA) technologies. In other examples, mobile stations may operate according to full rate or half rate vocoder technologies.
These different modes may determine different operating characteristics of the mobile station. In one example, the operating mode determines whether the mobile station utilizes full rate vocoder capabilities, or, alternatively, both full and half rate vocoder capabilities. Being able to operate the mobile station according to different modes allows the mobile station to operate more efficiently and effectively as it moves across different operational environments.
Unfortunately, situations exist where it is difficult or impossible to operate mobile stations according to multiple types of technologies or protocols. For example, when full rate capable mobile stations attempt to affiliate with a half-rate vocoder talk group, the full rate vocoder capable mobile station will not be able to communicate with the talk group since the talk group uses half-rate vocoder technology signaling and full rate vocoder capable mobile stations cannot utilize half-rate vocoder signaling. Consequently, the mobile station is left without communication capabilities.
In another example, when a half-rate vocoder capable mobile station roams to a radio frequency (RF) site that does not support half-rate vocoder signaling (e.g., legacy full rate vocoder signaling), the mobile station will not be able to operate until the user changes to a talk group that supports full rate vocoder signaling. As with the previous example, the user is left without communication capabilities. Because of the above-mentioned problems, it is difficult for users to operate mobile stations in various operating modes, using different technologies, and according to different protocols as the user moves across different networks or across the same network.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.